Place Representations in the Human Visual System

描述（由申请人提供）：我们是在太空中移动的生物，这是我们存在的最基本的情况。几乎所有的行为都对我们的生存至关重要——寻找食物、寻找配偶、躲避捕食者——都需要在外部世界中导航。半个世纪的研究表明，人类和动物使用世界大尺度空间结构的认知“地图”来促进这种能力。用于形成这些地图的大部分信息最初都是从视觉中获得的。但这就提出了一个难题：我们如何将最初从特定视图和特定实例中获得的视觉空间信息转换为可用于导航规划的环境空间的视点不变表示？这里提出的研究将使用功能磁共振成像（fMRI）来解决这个问题。在先前工作的基础上，我们假设人类大脑至少支持三种不同层次的空间表征：(1)它代表物体和表面相对于不同身体部位（如眼睛和手）的位置（身体空间）；(2)表示身体躯干与锚定在定义局部场景（场景空间）的一组不可移动表面上的坐标框架之间的关系；(3)它表示观察者在更大环境中的位置和方向，包括相对于当前“在地平线上”（世界空间）的位置。本研究的第一部分将研究海马体旁和脾后皮层的场景空间表征，特别强调揭示这些表征从经验中学习并随时间变化的机制。本研究的第二部分将研究表征身体空间的神经机制，并从功能上将这些机制与表征场景空间的神经机制区分开来。本研究的第三部分将研究表征世界空间的神经机制。虽然这项研究没有检查视力不佳的人的空间加工过程，但所获得的结果将帮助我们区分与视觉密不可分的过程和相对模态的过程。因此，这些知识对于盲人康复策略的发展至关重要。

DESCRIPTION (provided by applicant): There are few circumstances more fundamental to our existence in the fact that we are creatures that move through space. Almost all of the behaviors are essential to our survival - locating food, finding a mate, and avoiding predators - require navigation through the external world. A half-century of research suggests that humans and animals use cognitive "maps" of the large-scale spatial structure of the world to facilitate this ability. Much of the information used to form these maps is initially acquired from vision. But this presents a puzzle: how do we transform visuospatial information initially acquired from specific views and specific instances into a viewpoint-invariant representation of environmental space that can be used for navigational planning? The research proposed here will use functional magnetic resonance imaging (fMRI) to address this question. On the basis of previous work, we hypothesize that the human brain supports at least three distinct hierarchical levels of spatial representation: (1) it represents the locations of objects and surfaces relative to various body parts such as the eye and hand (body-space); (2) it represents the relationship between the trunk of the body and a coordinate frame anchored on the set of immovable surfaces that defines the local scene (scene-space); (3) it represents the the location and orientation of the observer within the larger environment, including relative to locations that are currently "over the horizon" (world-space). The first part of the proposed research will examine scene-space representations in parahippocampal and retrosplenial cortices with particular emphasis on uncovering the mechanisms by which these representations are learned from experience and change over time. The second part of the proposed research will examine the neural mechanisms involved in representing body-space and will functionally distinguish these mechanisms from those involved in representing scene-space. The third part of the proposed research will examine the neural mechanisms involved in representing world-space. Although this research does not examine spatial processing in nonsighted individuals, the results obtained will help us to distinguish between processes that are inextricably tied to vision and those that are relatively amodal. As such, this knowledge could be critical for development of rehabilitation strategies in the blind.